When you append an ampersand (&) to a command in Linux, it runs in the background. This isn't a big deal, but if you want to run the command in the foreground and see when it is done, leave off the ampersand.

cp -f /tmp/x.log /mnt/smbfs

Normally, the -f (force) option shouldn't be needed either, so again, if you want to shorten the amount one has to type,